Old 2018 keys often won't work on modern operating systems like Windows 11 without specific patches.
Unlike product keys, serial numbers are unique to each user's license. You can locate your specific serial number through the following official methods: Activating a Single-User AutoCAD 2018 License autodesk autocad 2018 product key and serial number
For those who still received DVDs or USB drives, the serial number was often printed on a sticker on the packaging. Old 2018 keys often won't work on modern
You simply sign in with an email address. The "key" is now your identity. ⚠️ A Note on Security and Compliance autodesk autocad 2018 product key and serial number